1. Field of the Invention
The present invention relates to a fabrication method of amorphous light rare earth-transition metal (LRE-TM) and metalloid alloy films, having uniaxial magnetic anisotropy energy perpendicular to the film planes.
2. Description of the Related Art
At present, an amorphous LRE-TM alloy has been highlighted as an information record-reproduction film material of a short wavelength magneto-optic recording media because of its characteristics in which the Kerr rotation angle increases in a short wavelength area.
In the prior art, an amorphous heavy rare-earth transition metal (HRE-TM) has been typically used as a recording film material of the red wavelength magneto-optic recording media. This HRE-TM alloy (e.g., TbFe) is mainly used as a red laser diode magneto-optic recording media because of its characteristics in which the Kerr rotation angle increases in a red laser wavelength. That is, as shown in the graph of FIG. 1, TbFe has an increasing Kerr rotation angle in a wavelength of 500 nm or more, thus it is appropriate as a red laser diode magneto-optic recording media having a wavelength between 600 nm and 700 nm. However, the recording density of the magneto-optic recording media is proportional to the square of the reciprocal of a laser wavelength. Thus, an improvement in the recording density requires use of a blue laser diode having a short wavelength. However, as shown in the graph of FIG. 1, TbFe increases the error generation rate due to its characteristics in which the Kerr rotation angle decreases in a blue laser wavelength.
In order to solve this problem, the LRE-TM alloy, which increases the Kerr rotation angle in a short wavelength area, has been highlighted as a recording film material of the magneto-optic recording media for a short wavelength. That is, as shown in the graph of FIG. 1, an amorphous NdFe metal alloy among LRE-TM alloys provides a high Kerr rotation angle in the short wavelength area, so it is appropriate as the recording film material of the magneto-optic recording media for a short wavelength. However, the LRE-TM alloy such as the NdFe alloy forms ferro-magnetic coupling between the magnetic moment of a light rare-earth metal and that of a transition metal, so it has much demagnetizing energy. Thus, the LRE-TM alloy does not have perpendicular magnetic anisotropy energy with respect to its plane but in-plane magnetic anisotropy energy, so that it cannot be used as a material for the recording film of the short-wavelength magneto-optic recording media.